[Feature]: Replace hand-craft hparams with dataclass and omegaconf framework

[Nugine]

Is your feature request related to a problem? Please describe.

The config file does not have a typed definition. IDE can not perform type check on config variables. It makes contributors harder to understand the codebase.

Describe the solution you'd like

• Use dataclasses to define structured config classes.
• Use omegaconf to load/save the config files.

[RMSnow]

Hi @Nugine, thanks for your insightful suggestions! We will investigate the two tools soon! (cc @Adorable-Qin)